Manage your lists, contexts and projects on your phone and synchronize the data back to Outlook. I don't have a Windows Smartphone but I saw an early demo of SmarterTasks, and it's a good-looking, intelligent GTD app that does things like auto-dial a phone number in tasks that contain keywords like "call", "phone" or "ring." A 30-day trial of SmarterTasks is available for download, $14.99 for a license, Windows Mobile 5.0 Smartphones only.